A reaction to prepare a secondary amine compound or a tertiary amine compound from a primary amine compound using a halide compound is frequently used in laboratory or for industrial purposes. However, when a primary amine compound is allowed to react with a halide compound so as to prepare a secondary amine compound, the secondary amine compound can react with the halide compound to produce a tertiary amine compound or an ammonium salt, because the nucleophilicity of the secondary amine compound can be greater than that of the primary amine compound. Namely, when the primary amine compound is allowed to react with the halide compound according to a general method, a mixture of the secondary amine compound, the tertiary amine compound and the ammonium salt can be produced, and the separation of the secondary amine compound from the mixture can be time-consuming and cost-ineffective.
Various methods have been attempted to obtain a secondary amine compound from a primary amine compound while minimizing the production of byproduct such as a tertiary amine compound or an ammonium salt. For example, a reductive alkylation reaction is known in which a secondary amine compound is prepared by allowing a primary amine compound to react with aldehyde or ketone to produce an imine compound which is then reduced with a reducing agent such as sodium borohydride or sodium cyanohydride (Ellen W. Baxter and Allen B. Reitz, Reductive Aminations of Carbonyl Compounds with Borohydride and Borane Reducing Agents, Organic Reactions, 1, 59, 2002). However, this method has shortcomings in that the reducing agent should additionally be used and aldehyde or ketone should be used in place of the halide compound. Also, a method is known in which a secondary amine compound is produced from a primary amine compound using a base such as cesium hydroxide monohydrate, potassium carbonate or triethylamine, but this method has disadvantages of long reaction time and high production cost.
Accordingly, there is a need for a method capable of effectively synthesizing a secondary amine compound from a primary amine compound while minimizing the generation of a tertiary amine compound or an ammonium salt.